DESCRIPTION: The long-term goal of the proposed studies is to understand the biochemical properties and cellular regulation of protein kinases that control myosin localization in Dictyostelium. The goal of the proposed studies is to describe the fundamental biochemical properties and structure of MHCK-A and the related MHCK B. Four specific aims are proposed: (1) To determine which residues and regions of MHCK A are involved in catalytic function and substrate binding; (2) to determine the biochemical and physiological substrate specificity of MHCK B; (3) to determine if there are conserved autoinhibitory or activating motifs in different members of the MHCK family of kinases; and (4) to determine the roles of the WD-repeat domain in MHCK A.